Corporate Banner
Satellite Banner
Molecular & Clinical Diagnostics
Scientific Community
 
Become a Member | Sign in
Home>News>This Article
  News
Return

A Cautionary Tale on Genome-Sequencing Diagnostics for Rare Diseases

Published: Tuesday, May 14, 2013
Last Updated: Tuesday, May 14, 2013
Bookmark and Share
Studies in several children have raising new questions about inheritance, genomic sequencing, and diagnostic.

Children born with rare, inherited conditions known as Congenital Disorders of Glycosylation, or CDG, have mutations in one of the many enzymes the body uses to decorate its proteins and cells with sugars. Properly diagnosing a child with CDG and pinpointing the exact sugar gene that's mutated can be a huge relief for parents—they better understand what they're dealing with and doctors can sometimes use that information to develop a therapeutic approach. Whole-exome sequencing, an abbreviated form of whole-genome sequencing, is increasingly used as a diagnostic for CDG.

But researchers at Sanford-Burnham Medical Research Institute (Sanford-Burnham) recently discovered three children with CDG who are mosaics—only some cells in some tissues have the mutation. For that reason, standard exome sequencing initially missed their mutations, highlighting the technique's diagnostic limitations in some rare cases. These findings were published April 4 in the American Journal of Human Genetics.

"This study was one surprise after another," said Hudson Freeze, Ph.D., director of Sanford-Burnham's Genetic Disease Program and senior author of the study. "What we learned is that you have to be careful—you can't simply trust that you'll get all the answers from gene sequencing alone."

Searching for a rare disease mutation

Complicated arrangements of sugar molecules decorate almost every protein and cell in the body. These sugars are crucial for cellular growth, communication, and many other processes. As a result of a mutation in an enzyme that assembles these sugars, children with CDG experience a wide variety of symptoms, including intellectual disability, digestive problems, seizures, and low blood sugar.

To diagnose CDG, researchers will test the sugar arrangements on a common protein called transferrin. Increasingly, they'll also look for known CDG-related mutations by whole-exome sequencing, a technique that sequences only the small portion of the genome that encodes proteins. The patients are typically three to five years old.

A cautionary tale for genomic diagnostics

In this study, the researchers observed different proportions and representations of sugar arrangements depending on which tissues were examined. In other words, these children have the first demonstrated cases of CDG "mosaicism"—their mutations only appear in some cell types throughout the body, not all. As a result, the usual diagnostic tests, like whole-exome sequencing, missed the mutations. It was only when Freeze's team took a closer look, examining proteins by hand using biochemical methods, did they identify the CDG mutations in these three children.

The team then went back to the three original children and examined their transferrin again. Surprisingly, these readings, which had previously shown abnormalities, had become normal. Freeze and his team believe this is because mutated cells in the children's livers died and were replaced by normal cells over time.

"If the transferrin test hadn't been performed early on for these children, we never would've picked up these cases of CDG. We got lucky in this case, but it just shows that we can't rely on any one test by itself in isolation," Freeze said.


Further Information

Join For Free

Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 3,200+ scientific posters on ePosters
  • More than 4,600+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.


Scientific News
Proteins in Blood of Heart Disease Patients May Predict Adverse Events
Nine-protein test shown superior to conventional assessments of risk.
£14m EU Project To Aid Meningitis Diagnosis and Cut Antibiotic Use
An international team of doctors are aiming to develop a rapid test to allow medics to quickly identify bacterial infection in children.
Bringing AFM to Medical Diagnostics
Company has announced that its NanoWizard® AFM and ForceRobot® systems are being used in the field of medical diagnostics in the Supersensitive Molecular Layer Laboratory of POSTECH in Korea.
Scientific Gains May Make Electronic Nose the Next Everyday Device
UT Dallas team breathes new life into possibilities by using CMOS integrated circuits technology.
Electronic Sensor Tells Dead Bacteria From Live
The sensor, which measures 'osmoregulation', is a potential future tool for medicine and food safety.
Diagnosing Systemic Infections Quickly, Reliably
Team develop rapid and specific diagnostic assay that could help physicians decide within an hour whether a patient has a systemic infection and should be hospitalized for aggressive intervention therapy.
A Future Tool for Medicine, Food Safety
A new type of electronic sensor that might be used to quickly detect and classify bacteria for medical diagnostics and food safety has passed a key hurdle by distinguishing between dead and living bacteria cells.
Genome Sequencing Helps Determine End of TB Outbreak
Using genome sequencing, researchers from the University of British Columbia, along with colleagues at the Imperial College in London, now have the ability to determine when a tuberculosis (TB) outbreak is over.
What Makes a Good Scientist?
It’s the journey, not just the destination that counts as a scientist when conducting research.
Shimmer Partners with Harvard's Wyss Institute
Partnership to support ongoing research focused on remote patient monitoring using wearable sensing technology.
SELECTBIO

SELECTBIO Market Reports
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
3,200+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,600+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FOR FREE!